Managing Safety
The role of human factors
By Jacqueline Booth-Bourdeau
March 2000
Jacqueline Booth-Bourdeau is a Technical Officer with Transport Canada's Aircraft Maintenance and Manufacturing Branch. She is responsible for human factors and safety issues affecting aircraft maintenance. Jacqueline holds Bachelor's and Master's Degrees and is currently studying aviation safety and quality assurance
Much has been said in the past few years about the role of the "human factor" in maintenance error. Statistically speaking this attention is warranted given that the percentage of incidents attributable to mechanical failures are declining, while incidents attributable to human performance are increasing. In the man versus machine interface, mankind is definitely becoming the more unreliable partner. Indeed, the increased confidence in the reliability of the machine, has placed the focus for improvements in safety squarely on the shoulders of the human element. With increased awareness and the abundance of literature available, neither companies nor regulators can afford to ignore the impact that human performance has upon aviation safety. If we bring technology into the equation, and mix in the increasing complexity of aircraft, the need for addressing human factors within aviation safety becomes vital.
Since 1989, when Canada had its own wake-up call with the crash of flight 1363 in Dryden, Ontario, we've tried to address the issue of the "human factor" head-on. Indeed, the subsequent Moshansky Commission of Inquiry into the Dryden accident resulted in numerous human factors recommendations, many of which are reflected in the new Canadian Aviation Regulations (CARs).
In introducing the concept of human factors as an integral part of the safety regulations, we have been careful to avoid the "knee jerk" reaction that an incident such as Dryden can have on the regulatory regime. While avoiding the urge to be prescriptive, we have also attempted to integrate a pro-active approach to safety through built in countermeasures.
If we look at the twelve most common influences affecting human performance, which include: fatigue, stress, and a lack of knowledge; and then look at Subpart 573 of the CARs - Approved Maintenance Organizations, it is clear that we address many of these issues in a dynamic, yet flexible way.
Human factors countermeasures
To demonstrate this, let's take a closer look at the human factors countermeasures we've built in to the regulations as a buffer against a lack of knowledge. Lack of knowledge, a common and understandable problem, particularly with new employees and apprentices, also affects seasoned maintenance professionals, especially when new products and procedures are introduced into a company. CAR 573.06 makes provision for all of these circumstances by requiring that Approved Maintenance Organizations implement a training program that ensures all employees, who perform or supervise maintenance, receive training in the procedures applicable to that function. Standard 573 of the Airworthiness Manual details the type of training that must be given: initial, recurrent and update training.
To ensure that maintenance personnel have the necessary training to competently perform their duties, CAR 573.09 requires that an AMO establish a quality assurance program. The goal here is to make sure that personnel have sufficient knowledge to ensure the correct performance of critical maintenance tasks. Where weaknesses are identified, the CARs require that additional training be given.
While this is a good start, we realize that there is more work to be done. To this end, we are in the process of introducing the requirement for all personnel with technical responsibilities to have initial and recurrent human factors training. Of course, human factors training and awareness is not the end of the story; nor is government regulation. It is our firm belief that for any human factors program to be successful, there has to be a commitment at the management level.
Safety culture framework
And, it's one thing to ensure that all of your employees have human factors training, but it's another thing to implement a safety program
in which human factors is an integral part of the way you do business. Without the attendant safety culture that's essential to all successful safety programs, the benefits of human factors interventions on the shop floor will simply be lost.
We realize, of course, that a "safety culture" is not something that can be regulated. As a government agency we can, however, provide the framework, which if applied correctly, will lead to its development. In conjunction with the human factors training requirement, we will be submitting a Notice of Proposed Amendment (NPA) to the CARs providing for the implementation of a Maintenance Safety Program in all AMOs and Air Operators with ratings in the Transport and Commuter categories. The concept is not new in Canada — there is an existing requirement in the operations side of the house. This NPA merely extends the requirement to cover maintenance, thereby completing the safety management picture.
In brief, this regulation will require organizations to conduct a hazard analysis of their procedures, conduct on-going safety audits, provide error analysis and information feedback, and communicate safety findings within the workplace. To reinforce the importance of the role of management in setting the level and tone of safety within the company, the certificate holder or accountable executive is responsible for the program.
In the ten years since Dryden, we've come a long way towards recognizing the importance of human factors in aviation incidents. Moreover, we have recognized that addressing individual human performance is only one piece of the safety puzzle. Without the commitment of the entire company to make safety, and not economics, priority number one; classic human factors interventions that empower and educate maintenance personnel will continue to be diminished. We have also realized that aviation safety cannot be assessed from a singular perspective — maintenance is just one of the links in the chain of events that lead to aviation incidents.
"Error is a natural human tendency," as James Reason states. "Recognizing the fallibility of humankind is just another foreseeable hazard in aviation." The issue is not why the error occurred, but how it failed to be corrected.
Samuel Smiles once said "We often discover what will do, by finding out what will not do; and probably he who never made a mistake, never made a discovery."
The point here is that we need to learn from our mistakes and implement the measures necessary to reduce human errors in maintenance. We have to recognize the types of mistakes being made and develop countermeasures to prevent their reoccurrence. In some cases, this might involve a real commitment on the part of management to radically change the organizational factors that create the latent conditions that lead to error. Whatever the solution is, it's becoming clear that the only real way to achieve a reduction in the rate of accidents and incidents is to address the prime cause —the human factor.
Frequently Asked Questions About Engine Oil
From AeroShell's Ben Visser
March 2000
The following questions are those most commonly asked by the aviation
community and are answered here by Ben Visser, Shell staff research engineer at AeroShell's Westhollow Technology Center:
Are multigrade and single grade oils compatible?
The compatibility question covers two issues: mixing one type of oil with another; and the effects on the engine of changing from one
type to the other.
If the engine typically runs on multigrade, and the pilot finds themselves in a place where only single grades are available, they can safely add the single grade to the engine. They are completely compatible.
If the engine runs on a single grade during the summer, but want to switch over to 15W-50 for the winter, you can safely replace the straight weight with the multigrade at the regular drain interval.
The idea that you have to stick with the type of oil you started with comes from the days unusual chemistry was done and was incompatible.
All approved MIL-L-22851/SAE J-1899 and MIL-L-6082/SAE J-1966 oils are compatible. For example, if you have a high-time engine run on ashless dispersant oils and need to replace a cylinder, you can switch to a mineral oil for 50 hours or so to break in the new cylinder.
The only time I recommend against switching is in a high-time engine run exclusively on straight mineral oil. Here, a switch to ashless dispersant oil can loosen deposits left behind by the mineral oil.
Will the oil temperature be higher or lower with a multigrade?
In most cases, the oil will run cooler. For a hot-running engine this is good, but for a cool-running plane it can be a disadvantage. If the engine runs too cool, it can't boil off excess moisture and unburned fuel, so there can be a tendency to form acid buildup.
For cooler-running engines, the operator should use a winterizing kit, or explore other methods of keeping oil temperature up.
What can I do to ensure the accuracy and value of an oil analysis?
Oil analyses can help you discover problems before they turn into major failures, but the formation gained is only as good as the sampling procedure.
Also, a single test is not enough to reveal trends and significant changes and can only tell you if there is already a serious problem like a scuffed piston.
Take samples properly. For best results, take the sample about midway through the draining of hot oil from the sump. A sample pulled off the bottom may be dirtier than normal. And do it the same way every time. An improperly taken sample can lead to some seriously mistaken conclusions about engine malfunctions.
Also, rely on a series of consistent tests over time. You're looking for significant changes or trends over time, not absolute values. People want to label the results of a single test as good or bad, but the system doesn't usually work that way. Say you're buying a used aircraft. Don't rely on just one very good result of just one report — it could have come from a 5- or 10-hour sample. Relatively constant numbers from the last six oil changes are a far better indicator that the engine is in good condition. This is helpful when selling an aircraft.
Be consistent. If you change the oil at 50 hours, and then at 25 hours the next time, the first sample may show twice the wear metals. (Expect higher wear metals during break-in or following some maintenance procedures such as a cylinder replacement.)
Finally, always remember that oil analysis should be part of a good maintenance program, not a replacement for one.
Is it necessary to change the oil filter at every oil change?
Yes. If you don't change the filter each time, the new oil will automatically start off with one quart of contaminated used oil. (Remember, the primary purpose for changing oil is to remove contaminants.) And new filters are simply more effective at trapping contaminants.
Old filters can serve as an excellent indicator of engine condition. An old filter that's been removed and cut open can provide an indication of the engine's condition by the amount and size of the particles in the filter. Champion sells an oil filter cutter and provides a detailed explanation of its use in their service manual AV6-R. If your engine isn't equipped with an oil filter, the pressure screen should be monitored.
When I drain my oil, should the engine be hot?
Yes. This can be very difficult on some aircraft, but it is recommended. The reason for changing oil when the engine is hot is to avoid the settling
of dirt and water in a cold engine. When the engine is fully warmed, then drained, a higher percentage of contaminants are drained away with the old oil. When the engine is drained cold, more of these contaminants remain in the oil in the bottom of the pan, which results in more contaminants mixing with the new oil.
Why does oil turn black between oil changes, and why does the time it takes to change color vary?
When a straight mineral oil turns dark or black, it usually means that the oil is starting to oxidize and needs to be changed. Because mineral oil doesn't absorb much of the dirt and sludge in your engine, the oil stays clean and the inside of your engine gets dirty. Ashless dispersant oils, on the other hand, are designed to get dirty so that the engine will stay clean. Just how quickly the oil turns black depends on a number of factors, including the condition of the engine, the dirt load, the oil temperature, the normal mixture strength, the type of fuel, the time since service, and the frequency and duration of the flights.
How can I determine which oil is qualified for an aircraft engine?
Both Lycoming and Continental recommend only oils qualified under the following specifications for use in their engines:
MIL-L-22851/SAE J-1899 (for ashless dispersant oils)
